Microbial enzymes exist for catalyzing the depolymerization of plant cell wall polysaccharides allowing the carbon in the plant cell walls to be recycled into free sugars that ultimately are metabolized to CO2. An emerging application of microbial enzymes is for conversion (e.g., deconstruction or digestion) of lignocellulosic materials (e.g., corn stover) into fermentable sugars useful for ethanol production. However, while mixtures of microbial enzymes have been isolated from fermentation vats of Trichoderma, such mixtures are expensive and do not contain optimal amounts or types of enzymes. The high cost of commercially available enzyme mixtures is currently a significant barrier to the development of a viable lignocellulosic biofuel industry. See, e.g., Banerjee et al., Bioenergy Res. 3:82-92 (2010); and Yang et al., Biofuels 2:421-450 (2011).
What are needed are methods and compositions that make the lignocellulosic conversion enzyme mixtures more efficient, thereby reducing their cost when expressed as dollars per gallon of ethanol.